While walking or running, the feet are engaged in the continuous movement of taking repeated steps. These steps can be broken down into different actions. Each step begins when the heel of one foot strikes the ground. The foot continues moving forward in a rolling fashion through to the toes. As seen in FIG. 1, the toes reach the ground during this phase of the step while, simultaneously, the heel begins to rise (points A and B). Once the toes touch the ground, the foot must carry through the step by further raising the heel. This motion is represented in FIG. 2. Point C of FIG. 2 represents the height the heel must reach in order to complete a step. Raising the heel during this stage of the step causes the foot to bend in the area of the five metatarsal Metatarsal-phalangeal joints, also referred to as the five metatarsal heads of the forefoot (see FIG. 5), and the skin in the area of the forefoot stretches. FIG. 3, angle DD shows the angle of the bend at the five metatarsal phalangeal joints. The bending occurrence in the area of the five Metatarsal-phalangeal joints of the forefoot is easily discernable in shoes that often have a crease in the area where this bending occurs, as shown in point D of FIG. 2. Once the heel reaches the necessary height, the foot breaks contact with the ground and returns to a straight position while the second foot begins its step, repeating the process.
Raising the heel in the course of taking a step causes the foot to bend in the area of the five metatarsal heads of the forefoot, necessarily stretching the skin in this area and possibly causing friction. People who have diabetes and other diseases that affect the feet face greater risks; bending the skin in the area of five metatarsal heads can crack the skin, which may lead to severe and painful wounds.
For people so afflicted, even minor injuries can take long periods to heal, and can grow worse over time if not treated properly. Therefore, any condition that may potentially damage the skin must be avoided. However, existing shoes and insoles do not provide the room necessary to complete a step with significantly reduced bending of the foot. This means the skin in the area of the five metatarsal heads of the forefoot is constantly exposed to potential damage. Currently, no preventive actions or devices exist to correct such limitations in existing shoes and insoles and to protect the skin in the area of the metatarsal heads from bending, stretching, and cracking.